1. Technical Field
The described embodiment relates generally to the use of an ultrasonic welding machine in electronics manufacturing.
2. Related Art
One common way to affix wires to a printed circuit board (PCB) is with a hot press. Wires are laid on top of a PCB pad with a certain amount of solid adhesive applied on the PCB pad. A pneumatic arm presses a heated pad down on to the wires and adhesive, melting the adhesive and embedding the wires within the adhesive. Unfortunately, to accomplish this with a high degree of reliability, the mechanical tolerances on the hot press must be quite precise. Both the distance the arm brings the heated pad down, and the pressure with which it pushes the wire into the adhesive, must be quite accurate. Consequences of inaccuracies can include improper adhesion of the wires, adhesive splash on neighboring components and even cracking or breaking of the PCB in extreme cases. The cost of precision machinery capable of delivering the requisite tolerances needed to make this manufacturing technique reliable is quite high. Even when adhesion is achieved, the melting process involved with the hot press process results in a phenomenon known in the industry as electromigration. When the bonding agent is heated small portions of it actually vaporize and are deposited across the area of the PCB itself. Electromigration can cause any number of undesirable consequences, such as for example, corrosion of electrical components and even short-circuiting.
Therefore, what is desired is a manufacturing tool capable of adhering the wires to the PCB pad in a reliable, repeatable way at a lower overall cost, without the need for volatile adhesives.